1. Field of the Invention
The invention relates to a wood planing machine, more particularly to a wood planing machine which is provided with a carriage locking mechanism for releasably locking a cutter carriage thereof.
2. Description of the Related Art
Referring to FIGS. 1 and 2, a conventional wood planing machine is shown to include a machine base 10, left and right pairs of posts 11, a cutter carriage 12, and a carriage locking mechanism.
As illustrated, the machine base 10 has opposite mounting sides 100 spaced apart from each other in a longitudinal direction, and opposite feed-in and take-out sides spaced apart from each other in a transverse direction. The left and right pairs of posts 11 extend upward from the machine base 10 at the mounting sides 100. The cutter carriage 12 is disposed above the machine base 10, and has opposite end portions mounted movably on the posts 11 for sliding movement along the left and right pairs of posts 11. A cutter device (not shown) is mounted on the cutter carriage 12 in a known manner, and is rotatable about a horizontal axis that extends in the longitudinal direction.
Left and right threaded rods 13 are mounted rotatably on, and extend upwardly from the machine base 10 at the mounting sides 100 to pass threadedly through the opposite end portions of the cutter carriage 12. The threaded rods 13 are interconnected in such a manner to rotate synchronously. A rotary handle 14 is provided at the top end of one of the threaded rods 13 such that rotation of the latter will cause the cutter carriage 12 to slide vertically along the left and right pairs of posts 11 so as to define a gap between the cutter carriage 12 and the machine base 10 for passage of a workpiece to be processed. A top cover 17 is fixed to the left and right pairs of posts 11 above the cutter carriage 12.
The carriage locking mechanism includes a manually operable handle 16, two locking linkages 15 mounted respectively on two opposite ends of the handle 16, and four post clamps 155 (only three are shown in FIG. 1) carried on the cutter carriage 12 and associated with the posts 11, respectively. Each of the locking linkages 15 includes first and second links 151,152 connected pivotally to each other at inner ends thereof and to the handle 16, and further connected pivotally to an adjacent pair of the post clamps 155 at outer ends thereof. Each of the second links 152 consists of a front connecting rod 154 that is connected pivotally to a respective one of the first links 151, a rear sliding piece 153 that is connected movably to the front connecting rod 154 and a respective one of the post clamps 155 at two ends thereof, and a compression spring 156 that interconnects the front connecting rod 154 and the rear sliding piece 153. As such, the springs 156 bias the post clamps 155 to abut against the posts 11, respectively, when the carriage locking mechanism is at a releasing position, as shown in FIG. 2. When adjustment to a desired carriage height has been achieved, the handle 16 is operated to move downward against biasing action of the springs 156 so as to move the carriage locking mechanism from the releasing position to a locking position, where the post clamps 155 are forced to press against the posts 11, respectively. At the locking position, the first and second links 151,152 are disposed on a straight line (not shown). Thus, the carriage 12 is locked relative to the left and right pairs of posts 11 so as to retain the same at a selected height relative to the machine base 10.
One disadvantage that results from the use of the aforesaid conventional wood planing machine resides in that in order to release the cutter carriage 12 from the left and right pairs of posts 11, the handle 16 must be moved upward. In this condition, the handle 16 will prop upward swiftly by virtue of biasing action of the springs 156. As such, the hands of the operator may collide against the top cover 17, thereby possibly injuring the operator.